rear hum after shutoff

crdouger

Veteran Member
Joined
Jan 16, 2010
Location
Michigan
TDI
99.5 & 06 jetta TDI's
I have a 2012 passat and everytime I drive it more than just a few feet, I hear a noise coming from the rear of the car. I think its the passenger side where the DEF tank is. When I shut off the car, it is quiet for a few seconds and then there is a quiet whirring sound or quiet hum that continues for maybe 30 seconds. It almost sounds like an air pump pumping up the suspension to level the car or something. But I don't think the car has that feature. It doesn't really sound like something is wrong, but puzzles me that I don't know what it is.

Thoughts?
 

crdouger

Veteran Member
Joined
Jan 16, 2010
Location
Michigan
TDI
99.5 & 06 jetta TDI's
Interesting. I don't know much about the DEF system. Apparently it empties the lines. My wifes 2013 doesn't seem to do that. Is it quieter or did they change the system?
 

BKmetz

Administrator, Member #10
Staff member
Joined
Sep 25, 1997
Location
Illinois
TDI
2015 Passat, titanium beige, 6MT
The Golfs, Jettas, and Beetles didn't get DEF until 2015 with the new EA288 engine family. In the older models, VW was able to meet emission requirement through fuel timing and EGR usage.

The NMS Passats had DEF from the beginning because those are heavier cars and needed DEF to meet emissions requirements.

:)
 

740GLE

Top Post Dawg
Joined
Aug 19, 2009
Location
NH
TDI
2015 Passat SEL, 2017 Alltrack SE; BB 2010 Sedan Man; 2012 Passat,
whats the outside temps now?

i think it empties the lines if there's a chance of freezing but if it's warm out it won't.
 
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